Gamma secretase inhibitors

ABSTRACT

Gamma-secretase inhibitors, useful in the treatment or prevention of Alzheimer&#39;s disease, are disclosed. The preferred compounds have, as the central portion of the molecule, the structure (a) and are diastereoisomers of known protease inhibitors.

[0001] The present invention relates to compounds, their salts,pharmaceutical compositions comprising them, processes for making themand their use in treating Alzheimer's Disease.

[0002] Alzheimer's Disease (AD) is characterised by the abnormaldeposition of amyloid in the brain in the form of extra-cellular plaquesand intra-cellular neurofibrillary tangles. The rate of amyloidaccumulation is a combination of the rates of formation, aggregation andegress from the brain. It is generally accepted that the mainconstituent of amyloid plaques is the 4kD amyloid protein (βA4, alsoreferred to as Aβ,β-protein and βAP) which is a proteolytic product of aprecursor protein of much larger size. The ragged NH₂- and COOH-terminiof the native Aβ amyloid indicates that a complex mechanism ofproteolysis is involved in its biogenesis.

[0003] The amyloid precursor protein (APP or AβPP) has a receptor-likestructure with a large ectodomain, a membrane spanning region and ashort cytoplasmic tail. Different isoforms of APP result from thealternative splicing of three exons in a single gene and have 695, 751and 770 amino acids respectively.

[0004] The Aβ domain encompasses parts of both extra-cellular andtransmembrane domains of APP, thus its release implies the existence oftwo distinct proteolytic events to generate its NH₂- and COOH-termini.At least two secretory mechanisms exist which release APP from themembrane and generate the soluble, COOH-truncated forms of APP(APP_(s)). Proteases which release APP and its fragments from themembrane are termed “secretases”. Most APP_(s) is released by a putativeα-secretase which cleaves within the AD domain (between residues Lys¹⁶and Leu¹⁷) to release α-APP_(s) and precludes the release of intact Aβ.A minor portion of APP_(s) is released by a β-secretase, which cleavesnear the NH₂-terminus of Aβ and produces COOH-terminal fragments (CTFs)which contain the whole Aβ domain. Finding these fragments in theextracellular compartment suggests that another proteolytic activity(γ-secretase) exists under normal conditions which can generate theCOOH-terminus of Aβ.

[0005] It is believed that γ-secretase itself depends for its activityon the presence of presenilin-1. In a manner that is not fullyunderstood presenilin-1 appears to undergo autocleavage.

[0006] The compounds of the present invention are useful for treating ADby inhibiting the activity of the putative γ-secretase thus preventingthe formation of insoluble Aβ and arresting the production of Aβ.Further, some of the present compounds also stabilise full-lengthpresenilin-1.

[0007] In a further aspect some of the compounds of the presentapplication are useful as inhibitors of presenilin-1 cleavage.

[0008] The compounds of the present invention are related to HIVprotease inhibitors described in EP-A-337 714 and EP-A-356 223, both inthe name of Merck & Co., Inc.. These compounds are aspartyl proteaseinhibitors. Specifically, a subset of the compounds of the presentinvention differ from those previously described by the stereochemistryof a hydroxyl group which is a particularly preferred feature of thepresent invention and has not previously been disclosed for theseparticular compounds. This is a surprising feature giving rise to thepresent invention.

[0009] The present invention, in one aspect, provides a compoundcomprising the group:

[0010] wherein R² and R³ are as defined below, which compound is adiastereoisomer of a known protease inhibitor comprising the group

[0011] wherein R² and R³ are as defined below.

[0012] The present invention accordingly provides a compound of formulaI or a pharmaceutically acceptable salt thereof:

[0013] wherein:

[0014] R¹ is (1) C₁₋₁₀alkyl, C₂₋₁₀alkenyl or C₂₋₁₀alkynyl optionallysubstituted with one to three substituents independently chosen from:

[0015] (i) hydroxy;

[0016] (ii) carboxy;

[0017] (iii) halogen;

[0018] (iv) C₁₋₄alkoxy;

[0019] (v) C₁₋₄alkoxycarbonyl;

[0020] (vi) —NR⁶R⁷ wherein R⁶ and R⁷ are independently chosen fromhydrogen, C₁₋₅alkyl and C₁₋₅alkoxyC₁₋₅alkyl;

[0021] (vii) —CONR⁶R⁷ or OCONR⁶R⁷ wherein R⁶ and R⁷ are independently asdefined above;

[0022] (viii) —N(R⁸)QR⁹ wherein:

[0023] Q is C(O), C(S), SO₂ or C(NH₂);

[0024] R⁸ is hydrogen or C₁₋₄alkyl; and

[0025] R⁹ is hydrogen, C₁₋₄alkyl, C₁₋₄alkoxy, amino, C₁₋₄alkylaminodi(C₁₋₄alkyl)amino wherein each alkyl group is independently chosen;

[0026] (ix) C₃₋₇cycloalkyl;

[0027] (x) phenyl or naphthyl; a five-membered heterocyclic ringcontaining 1, 2, 3 or 4 heteroatoms independently chosen from O, N andS, at most one of the heteroatoms being O or S; a six-memberedheterocyclic ring containing 1, 2 or 3 nitrogen atoms; each of which isoptionally substituted by one to three groups independently chosen from:

[0028] (a) halogen, cyano and nitro,

[0029] (b) hydroxy,

[0030] (c) C₁₋₄alkyl, C₂₋₄alkenyl and C₂₋₄alkynyl,

[0031] (d) C₁₋₄alkoxy,

[0032] (e) NR⁶R⁷ wherein R⁶ and R⁷ are independently as defined above,

[0033] (f) CO₂R⁸ wherein R⁸ is independently as defined above,

[0034] (g) CONR⁶R⁷ or OCONR⁶R⁷ wherein R⁶ and R⁷ are independently asdefined above,

[0035] (h) SO₂NR⁶R⁷ wherein R⁶ and R⁷ are independently as definedabove,

[0036] (i) CH₂NR⁷R⁷ wherein R⁶ and R⁷ are independently as definedabove,

[0037] (j) N(R⁸)COR⁸′ wherein R⁸ is independently as defined above andR⁸′ is independently as defined for R⁸, and

[0038] (k) NR⁸SO₂R⁸′ wherein R⁸ and R⁸′ are independently as definedabove; or

[0039] (2) phenyl or naphthyl; a five-membered heterocyclic ringcontaining 1, 2, 3 or 4 heteroatoms independently chosen from O, N andS, at most one of the heteroatoms being O or S; a six-memberedheterocyclic ring containing 1, 2 or 3 nitrogen atoms; each of which isoptionally substituted by one to three groups independently chosen from:

[0040] (a) halogen, cyano and nitro,

[0041] (b) hydroxy,

[0042] (c) C₁₋₄alkyl, C₂₋₄alkenyl and C₂₋₄alkynyl,

[0043] (d) C₁₋₄alkoxy,

[0044] (e) NR⁶R⁷ wherein R⁶ and R⁷ are independently as defined above,

[0045] (f) CO₂R⁸ wherein R⁸ is independently as defined above,

[0046] (g) CONR⁶R⁷ or OCONR⁶R⁷ wherein R⁶ and R⁷ are independently asdefined above,

[0047] (h) SO₂NR⁶R⁷ wherein R⁶ and R⁷ are independently as definedabove,

[0048] (i) CH₂NR⁶R⁷ wherein R⁶ and R⁷ are independently as definedabove,

[0049] (j) N(R⁸)COR⁸′ wherein R⁸ and R⁸′ are independently as definedabove, and

[0050] (k) NR⁸SO₂R⁸′ wherein R⁸ and R⁸′ are independently as definedabove;

[0051] R² and R³ are independently chosen from C₁₋₁₀alkyl, C₁₋₁₀alkoxy,C₂₋₁₀alkenyl, C₂₋₁₀alkenyloxy, C₂₋₁₀alkynyl or C₂₋₁₀alkynyloxy; phenyl;naphthyl; a five-membered heteroaromatic ring containing 1, 2, 3 or 4heteroatoms independently chosen from O, N and S, at most one of theheteroatoms being O or S; a six-membered heteroaromatic ring containing1, 2 or 3 nitrogen atoms; and a group (CH₂)_(p)Q¹ wherein Q¹ is phenyl,naphthyl, a five-membered heteroaromatic ring containing 1, 2, 3 or 4heteroatoms independently chosen from O, N and S, at most one of theheteroatoms being O or S, and a six-membered heteroaromatic ringcontaining 1, 2 or 3 nitrogen atoms; and wherein each of R² and R³ isindependently optionally substituted by one to three groupsindependently chosen from:

[0052] (a) halogen, cyano and nitro,

[0053] (b) hydroxy,

[0054] (c) C₁₋₃alkyl, C₂₋₃alkenyl and C₂₋₃alkynyl,

[0055] (d) C₁₋₃alkoxy,

[0056] (e) NR⁶R⁷ wherein R⁶ and R⁷ are independently as defined above,

[0057] (f) CO₂R⁸ wherein R⁸ is independently as defined above,

[0058] (g) CONR⁶R⁷ or OCONR⁶R⁷ wherein R⁶ and R⁷ are independently asdefined above,

[0059] (h) SO₂NR⁶R⁷ wherein R⁶ and R⁷ are independently as definedabove,

[0060] (i) CH₂NR⁶R⁷ wherein R⁶ and R⁷ are independently as definedabove,

[0061] (j) N(R⁸)COR⁸′ wherein R⁸ and R⁸′ are independently as definedabove,

[0062] (k) NR⁸SO₂R⁸′ where R⁸ and R⁸′ are independently as definedabove;

[0063] alternatively R³ may be hydrogen;

[0064] R⁴ and R⁵ are independently chosen from hydrogen, C₁₋₆alkyloptionally substituted by halogen, hydroxy, thiol, amino, C₁₋₄alkoxy,C₁₋₄ alkylthio, carboxy, C₁₋₄ alkoxycarbonyl and (CH₂)_(q)Q² wherein Q²is a five-membered unsaturated heterocycle containing 1, 2, 3 or 4heteroatom optionally chosen from O, N, and S providing that not morethan one heteroatom is O or S, a six-membered unsaturated heterocyclecontaining 1, 2 or 3 N atoms and phenyl and naphthyl, or a fused ringwhich is indolyl, each of the foregoing rings being optionallysubstituted with one to three groups independently chosen from hydroxy,C₁₋₄alkyl, C₁₋₄alkoxy, thiol, C₁₋₄alkylthio, halogen, amino, carboxy,amido, CO₂H and —NHC(NH₂)₂ and wherein each of the foregoing rings isoptionally fused to a benzene ring; and

[0065] A is:

[0066] (1) hydrogen;

[0067] (2) C₁₋₁₀alkyl, C₂₋₁₀alkenyl or C₂₋₁₀alkynyl optionallysubstituted with one to three substituents independently chosen from:

[0068] (i) hydroxy;

[0069] (ii) carboxy;

[0070] (iii) halogen;

[0071] (iv) C₁₋₄alkoxy;

[0072] (v) C₁₋₄alkoxycarbonyl;

[0073] (vi) —NR⁶R⁷ wherein R⁶ and R⁷ are independently chosen fromhydrogen, C₁₋₅alkyl and C₁₋₅alkoxyC₁₋₅alkyl;

[0074] (vii) —CONR⁶R⁷ or OCONR⁶R⁷ wherein R⁶ and R⁷ are independently asdefined above;

[0075] (viii) —N(R⁸)QR⁹ wherein:

[0076] Q is C(O), C(S), SO₂ or C(NH₂);

[0077] R⁸ is hydrogen or C₁₋₄alkyl; and

[0078] R⁹ is hydrogen, C₁₋₄alkyl, C₁₋₄alkoxy, amino, C₁₋₄alkylaminodi(C₁₋₄alkyl)amino wherein each alkyl group is independently chosen;

[0079] (ix) C₃₋₇cycloalkyl;

[0080] (x) phenyl or naphthyl; a five-membered heterocyclic ringcontaining 1, 2, 3 or 4 heteroatoms independently chosen from O, N andS, at most one of the heteroatoms being O or S; a six-memberedheterocyclic ring containing 1, 2 or 3 nitrogen atoms; each of which isoptionally substituted by one to three groups independently chosen from:

[0081] (a) halogen, cyano and nitro,

[0082] (b) hydroxy,

[0083] (c) C₁₋₄alkyl, C₂₋₄alkenyl and C₂₋₄alkynyl,

[0084] (d) C₁₋₄alkoxy,

[0085] (e) NR⁶R⁷ wherein R⁶ and R⁷ are independently as defined above,

[0086] (f) CO₂R⁸ wherein R⁸ is independently as defined above,

[0087] (g) CONR⁶R⁷ or OCONR⁶R⁷ wherein R⁶ and R⁷ are independently asdefined above,

[0088] (h) SO₂NR⁶R⁷ wherein R⁶ and R⁷ are independently as definedabove,

[0089] (i) CH₂NR⁶R⁷ wherein R⁶ and R⁷ are independently as definedabove,

[0090] (j) N(R⁸)COR⁸′ wherein R⁸ is independently as defined above andR⁸′ is independently as defined for R⁸, and

[0091] (k) NR⁸SO₂R⁸ wherein R⁸ and R⁸′ are independently as definedabove; or

[0092] (3) a seven-membered heterocycle

[0093] having an otherwise unsubstituted carbon atom at the point ofattachment to the rest of the compound of formula I,

[0094] having at a first atom alpha to the point of attachment a carbonatom which is unsubstituted or substituted by an oxygen or sulphur atom,

[0095] having at a first atom beta to the point of attachment, whichatom is alpha to the foregoing first atom alpha, a carbon atom or anitrogen atom,

[0096] having at a second atom alpha to the point of attachment a carbonatom, which is optionally substituted by oxygen, or a nitrogen atom,

[0097] having at a second atom beta to the point of attachment, whichatom is alpha to the foregoing second atom alpha, a carbon atom or anitrogen atom,

[0098] and having at the two remaining atoms carbon atoms;

[0099] a double bond may be present between the second atom alpha andthe second atom beta;

[0100] the seven-membered heterocycle may be fused to one or twoaromatic rings via any adjacent pair of atoms other than the point ofattachment and the first atom alpha alone or in combination;

[0101] the aromatic ring may be benzene or a five-membered heterocyclecontaining 1, 2, 3 or 4 heteroatoms chosen from O, N and S providingthat not more than one heteroatom is O or S or a six-memberedheterocycle containing 1, 2 or 3 nitrogen atoms;

[0102] alternatively a pair of adjacent carbon atoms in theseven-membered heterocycle, other than the point of attachment and thefirst atom alpha alone or in combination, may form part of a fusedcyclopropyl or cyclopentyl ring;

[0103] one to three substitutable atoms of the seven-memberedheterocycle are optionally substituted by:

[0104] an aromatic ring as defined above optionally substituted byhydroxy, halogen, methoxy or alkyl having one to four carbon atoms;

[0105] an alkyl group having one to four carbon atoms optionallysubstituted by a halogen atom, hydroxy, an aromatic ring as definedabove optionally substituted by hydroxy, halogen, methoxy or alkylhaving one to four carbon atoms, cycloalkyl having three to seven carbonatoms, methoxy, bicycloalkyl having seven to twelve carbon atoms,heterocycle having five to seven atoms one of which is oxygen, nitrogenor sulphur which is optionally oxidized;

[0106] a heterocycle having five to seven atoms one of which is oxygen,nitrogen or sulphur which is optionally oxidized;

[0107] cycloalkyl having three to seven carbon atoms;

[0108] or bicycloalkyl having seven to twelve carbon atoms;

[0109] or the two groups A attached to the same nitrogen atom, togetherwith that atom, form: a five-membered heterocyclic ring optionallycontaining 1, 2 or 3 further heteroatoms chosen from O, N and S, notmore than one of the heteroatoms being O or S; or a six-memberedheterocyclic ring optionally containing 1 or 2 further nitrogen atoms;each of which is optionally substituted by one to three groupsindependently chosen from:

[0110] (a) halogen, cyano and nitro,

[0111] (b) hydroxy,

[0112] (c) C₁₋₄alkyl, C₂₋₄alkenyl and C₂₋₄alkynyl,

[0113] (d) C₁₋₄alkoxy,

[0114] (e) NR⁶R⁷ wherein R⁶ and R⁷ are independently as defined above,

[0115] (f) CO₂R⁸ wherein R⁸ is independently as defined above,

[0116] (g) CONR⁶R⁷ or OCONR⁶R⁷ wherein R⁶ and R⁷ are independently asdefined above,

[0117] (h) SO₂NR⁶R⁷ wherein R⁶ and R⁷ are independently as definedabove,

[0118] (i) CH₂NR⁶R⁷ wherein R⁶ and R⁷ are independently as definedabove,

[0119] (j) N(R⁸)COR⁸′ wherein R⁸ is independently as defined above andR⁸′ is independently as defined for R⁸, and

[0120] (k) NR⁸SO₂R⁸′ wherein R⁸ and R⁸′ are independently as definedabove;

[0121] B is C═O or CHOH in the R configuration;

[0122] X is oxygen or a bond;

[0123] n is zero or one, and

[0124] p is zero, one, two or three; and

[0125] q is zero, one, two or three;

[0126] with the proviso that no carbon atom is substituted by more thanone hydroxy group.

[0127] In an embodiment the compounds of the present invention are offormula I′:

[0128] where R¹, R², R³, R⁴, R⁵, A and n are as defined above.

[0129] In one embodiment the compounds of the present invention are offormula I″:

[0130] where R¹, R², R³, R⁴, R⁵, A and n are as defined above.

[0131] In another embodiment there are provided compounds of formulaI′″:

[0132] where R¹, R², R³, R⁴ and R⁵ are as defined above.

[0133] The following preferred definitions of substituents apply to eachof the formulae I, I′, I″ and I′″ which refer to those substituents.

[0134] Preferably R¹ is

[0135] (1) C₁₋₁₀alkyl, C₂₋₁₀alkenyl or C₂₋₁₀alkynyl optionallysubstituted with one to three substituents independently chosen from:

[0136] (i) hydroxy;

[0137] (ii) halogen;

[0138] (iii) amino;

[0139] (iv) C₁₋₄alkoxy; and

[0140] (v) phenyl which is optionally substituted by one or two groupsindependently chosen from:

[0141] (a) halogen, cyano and nitro,

[0142] (b) hydroxy,

[0143] (c) C₁₋₄alkyl, C₂₋₄alkenyl and C₂₋₄alkenyl,

[0144] (d) C₁₋₄alkoxy and

[0145] (e) amino; or

[0146] (2) phenyl which is optionally substituted by one or two groupsindependently chosen from:

[0147] (a) halogen, cyano and nitro,

[0148] (b) hydroxy,

[0149] (c) C₁₋₄alkyl, C₂₋₄alkenyl and C₂₋₄alkynyl,

[0150] (d) C₁₋₄alkoxy and

[0151] (e) amino.

[0152] When R¹ is a heterocyclic ring it may be saturated, partiallysaturated or unsaturated. Preferably the heterocyclic ring is aheteroaromatic ring.

[0153] More preferably R¹ is C₁₋₁₀alkyl optionally substituted with upto three substituents as defined above. Even more preferably R¹ isC₁₋₆alkyl optionally substituted by one to three substituents as definedabove. Most preferably R¹ is C₁₋₆alkyl optionally substituted byhalogen, phenyl, hydroxy or C₁₋₄alkoxy. In particular R¹ may be tertiarybutyl or benzyl.

[0154] R² and R³ may be independently chosen from phenyl; naphthyl; afive-membered heteroaromatic ring containing 1, 2, 3 or 4 heteroatomsindependently chosen from O, N and S, at most one of the heteroatomsbeing O or S; a six-membered heteroaromatic ring containing 1, 2 or 3nitrogen atoms; and a group (CH₂)_(p)Q¹ wherein Q¹ is phenyl; naphthyl;a five-membered heteroaromatic ring containing 1, 2, 3 or 4 heteroatomsindependently chosen from O, N and S, at most one of the heteroatomsbeing O or S; and a six-membered heteroaromatic ring containing 1, 2 or3 nitrogen atoms; and wherein each of R² and R³ is independentlyoptionally substituted by one to three groups independently chosen from:

[0155] (a) halogen, cyano and nitro,

[0156] (b) hydroxy,

[0157] (c) C₁₋₃alkyl, C₂₋₃alkenyl and C₂₋₃alkynyl,

[0158] (d) C₁₋₃alkoxy,

[0159] (e) NR⁶R⁷ wherein R⁶ and R⁷ are independently as defined above,

[0160] (f) CO₂R⁸ wherein R⁸ is independently as defined above,

[0161] (g) CONR⁶R⁷ wherein R⁶ and R⁷ are independently as defined above,

[0162] (h) SO₂NR⁶R⁷ wherein R⁶ and R⁷ are independently as definedabove,

[0163] (i) CH₂NR⁶R⁷ wherein R⁶ and R⁷ are independently as definedabove,

[0164] (j) N(R⁸)COR⁸′ wherein R⁸ and R⁸′ are independently as definedabove,

[0165] (k) NR⁸SO₂R⁸′ where R⁸ and R⁸′ are independently as definedabove;

[0166] More preferably R² and R³ are (CH₂)_(p)Q¹.

[0167] Preferably p is one.

[0168] Preferably Q¹ is phenyl optionally substituted by one or twogroups independently chosen from:

[0169] (a) halogen, cyano and nitro,

[0170] (b) hydroxy,

[0171] (c) C₁₋₄alkyl, C₂₋₄alkenyl and C₂₋₄alkynyl,

[0172] (d) C₁₋₄alkoxy and

[0173] (e) amino.

[0174] In one embodiment R² and R³ are both benzyl.

[0175] More preferably Q¹ is phenyl.

[0176] Preferably R⁴ and R⁵ are independently chosen from optionallysubstituted C₁₋₆alkyl and (CH₂)_(q)Q². More preferably R⁴ and R⁵ areindependently chosen from C₁₋₆alkyl and (CH₂)_(q)Q².

[0177] Preferably Q² is optionally substituted phenyl. More preferablyQ² is phenyl.

[0178] In particular R⁴ and R⁵ are independently chosen from methyl,benzyl, phenyl, 2-methylpropyl, 1-hydroxyethyl, isopropyl and isobutyl.

[0179] A is preferably hydrogen or a group

[0180] wherein R⁷ is phenyl, C₁₋₆alkyl or C₃₋₇cycloalkyl and Y ishydrogen or C₁₋₆ alkyl. More preferably A is hydrogen or a group asdefined above wherein R⁷ is a cyclohexyl group.

[0181] X is preferably oxygen.

[0182] n may be zero. n may be one.

[0183] p is preferably one.

[0184] q is preferably zero or one.

[0185] Thus a subclass of compounds of formula I and I′ is providedwherein:

[0186] R¹ is

[0187] (1) C₁₋₁₀alkyl, C₂₋₁₀alkenyl or C₂₋₁₀alkynyl optionallysubstituted with one or more substituents independently chosen from:

[0188] (i) hydroxy;

[0189] (ii) halogen;

[0190] (iii) amino;

[0191] (iv) C₁₋₄alkoxy; and

[0192] (v) phenyl which is optionally substituted by one or two groupsindependently chosen from:

[0193] (a) halogen, cyano and nitro,

[0194] (b) hydroxy,

[0195] (c) C₁₋₄alkyl, C₂₋₄alkenyl and C₂₋₄alkynyl,

[0196] (d) C₁₋₄alkoxy and

[0197] (e) amino; or

[0198] (2) phenyl which is optionally substituted by one or two groupsindependently chosen from:

[0199] (a) halogen, cyano and nitro,

[0200] (b) hydroxy,

[0201] (c) C₁₋₄alkyl, C₂₋₄alkenyl and C₂₋₄alkynyl,

[0202] (d) C₁₋₄ alkoxy and

[0203] (e) amino;

[0204] R² and R³ are both (CH₂)_(p)Q¹ wherein Q¹ is phenyl optionallysubstituted by one or two groups independently chosen from:

[0205] (a) halogen,

[0206] (b) hydroxy,

[0207] (c) C₁₋₄alkyl, C₂₋₄alkenyl and C₂₋₄alkynyl,

[0208] (d) C₁₋₄alkoxy and

[0209] (e) amino;

[0210] R⁴ and R⁵ are independently chosen from C₁₋₆alkyl optionallysubstituted by halogen, hydroxy, amino or C₁₋₄alkoxy and (CH₂)_(q)Q²wherein Q² is phenyl optionally substituted by hydroxy, C₁₋₄alkyl,C₁₋₄alkoxy, thiol, C₁₋₄alkylthio, halogen, amino, carboxy, amido, CO₂Hand —NHC(NH₂)₂;

[0211] A is hydrogen or

[0212] wherein R⁷ is phenyl, C₁₋₆alkyl or C₃₋₇cycloalkyl;

[0213] Y is hydrogen or C₁₋₆ alkyl;

[0214] n is zero or one;

[0215] p is one; and

[0216] q is zero or one.

[0217] For the avoidance of doubt each time the moieties A, R⁶, R⁷, R⁸,R⁸′ and R⁹ occur more than once in the definition of the compounds offormula (I) they are chosen independently.

[0218] As used herein, the expression “C₁₋₁₀alkyl” includes methyl andethyl groups, and straight-chained and branched propyl, butyl, pentyland hexyl groups. Particular alkyl groups are methyl, ethyl, n-propyl,isopropyl and t-butyl. Derived expressions such as “C₁₋₆alkyl”,“C₁₋₄alkyl”, “C₂₋₁₀alkenyl”, “C₂₋₄alkenyl”, “C₂₋₁₀ alkynyl” and“C₂₋₄alkynyl” are to be construed in an analogous manner.

[0219] The expression “C₃₋₇cycloalkyl” as used herein includes cyclicpropyl, butyl, pentyl, hexyl and heptyl groups such as cyclopropyl andcyclohexyl.

[0220] The term “heterocyclic” includes rings which are saturated,partially saturated or unsaturated. Unsaturated heterocyclic rings arealso known as heteroaromatic rings.

[0221] Suitable 5- and 6-membered heteroaromatic rings includepyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, pyrrolyl, pyrazolyl,oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, imidazolyl, oxadiazolyland thiadiazolyl groups. A suitable 5-membered heteroaromatic ringcontaining four nitrogen atoms is tetrazolyl. Suitable 6-memberedheteroaromatic rings containing three nitrogen atoms include1,2,4-triazine and 1,3,5-triazine. Suitable saturated heterocyclic ringsinclude piperazine, morpholine, piperidine, tetrahydrofuran andtetrahydrothiophene. Tetrahydrofuran is preferred.

[0222] The term “halogen” as used herein includes fluorine, chlorine,bromine and iodine, of which fluorine and chlorine are preferred.

[0223] As used herein the term “C₁₋₄alkoxy” includes methoxy and ethoxygroups, and straight-chained, branched and cyclic propoxy and butoxygroups, including cyclopropylmethoxy.

[0224] Specific Examples according to the present invention include:

[0225]{1S-benzyl-4R-[1-(1S-carbamoyl-2-(R)-hydroxypropylcarbamoyl)-(S)-ethylcarbamoyl]-2R-hydroxy-5-phenylpentyl}-carbamicacid, tert-butyl ester;

[0226]{1S-benzyl-4R-[1-(1S-carbamoyl-2-(S)-methylbutylcarbamoyl)-1S-2-methylpropylcarbamoyl]-2R-hydroxy-5-phenylpentyl}-carbamicacid, tert-butyl ester;

[0227]{1S-benzyl-4-[1-(5-cyclohexyl-2-oxo-2,3-dihydro-1H-benzo[e][1,4]diazepin-3(R,S)-ylcarbamoyl)-(S)-ethylcarbamoyl]-2R-hydroxybutyl}-carbamicacid, tert-butyl ester;

[0228]{1S-benzyl-4R-[1-(5-cyclohexyl-2-oxo-2,3-dihydro-1H-benzo[e][1,4]diazepin-3(R,S)-ylcarbamoyl)-(S)-ethylcarbamoyl]-2R-hydroxy-5-phenylpentyl}-carbamicacid, tert-butyl ester;

[0229]{1S-benzyl-4R-[1-(1S-carbamoyl-2-phenylethylcarbamoyl)-1S-3-methylbutylcarbamoyl]-2R-hydroxy-5-phenylpentyl}-carbamicacid, benzyl ester;

[0230]{1S-benzyl-4R-[1-(1S-carbamoyl-2-phenylethylcarbamoyl)-1S-3-methylbutylcarbamoyl]-2-oxo-5-phenylpentyl}-carbamicacid tert-butyl ester;

[0231]{1S-benzyl-4R-[1-(1S-carbamoyl-2-phenylethylcarbamoyl)-1S-3-methyl-butylcarbamoyl]-2R-hydroxy-5-phenylpentyl}carbamicacid tert-butyl ester;

[0232]{1S-benzyl-4R-[1-(1S-carbamoyl-2-phenylethylcarbamoyl)-S-ethylcarbamoyl]-2R-hydroxy-5-phenylpentyl}carbamicacid tert-butyl ester;

[0233](1S-benzyl-4R-{1S-[(carbamoylphenylmethyl)carbamoyl]-S-ethylcarbamoyl}-2R-hydroxy-5-phenylpentyl)carbamicacid tert-butyl ester;

[0234] and the pharmaceutically acceptable salts thereof.

[0235] Examples of pharmaceutically acceptable salts are hydrochlorides,sulfates, citrates, tartrates, acetates, methanesulfonates, phosphates,oxalates and benzoates.

[0236] The compounds of the present invention have an activity asinhibitors of γ secretase. In a preferred embodiment the compounds ofthe invention inhibit proteolysis of PS-1.

[0237] The invention also provides pharmaceutical compositionscomprising one or more compounds of this invention and apharmaceutically acceptable carrier. Preferably these compositions arein unit dosage forms such as tablets, pills, capsules, powders,granules, sterile parenteral solutions or suspensions, metered aerosolor liquid sprays, drops, ampoules, transdermal patches, auto-injectordevices or suppositories; for oral, parenteral, intranasal, sublingualor rectal administration, or for administration by inhalation orinsufflation. For preparing solid compositions such as tablets, theprincipal active ingredient is mixed with a pharmaceutical carrier, e.g.conventional tableting ingredients such as corn starch, lactose,sucrose, sorbitol, talc, stearic acid, magnesium stearate, dicalciumphosphate or gums or surfactants such as sorbitan monooleate,polyethylene glycel, and other pharmaceutical diluents, e.g. water, toform a solid preformulation composition containing a homogeneous mixtureof a compound of the present invention, or a pharmaceutically acceptablesalt thereof. When referring to these preformulation compositions ashomogeneous, it is meant that the active ingredient is dispersed evenlythroughout the composition so that the composition may be readilysubdivided into equally effective unit dosage forms such as tablets,pills and capsules. This solid preformulation composition is thensubdivided into unit dosage forms of the type described above containingfrom 0.1 to about 500 mg of the active ingredient of the presentinvention. Typical unit dosage forms contain from 1 to 100 mg, forexample 1, 2, 5, 10, 25, 50 or 100 mg, of the active ingredient. Thetablets or pills of the novel composition can be coated or otherwisecompounded to provide a dosage form affording the advantage of prolongedaction. For example, the tablet or pill can comprise an inner dosage andan outer dosage component, the latter being in the form of an envelopeover the former. The two components can be separated by an enteric layerwhich serves to resist disintegration in the stomach and permits theinner component to pass intact into the duodenum or to be delayed inrelease. A variety of materials can be used for such enteric layers orcoatings, such materials including a number of polymeric acids andmixtures of polymeric acids with such materials as shellac, cetylalcohol and cellulose acetate.

[0238] The present invention also provides a compound of the inventionor a pharmaceutically acceptable salt thereof for use in a method oftreatment of the human body. Preferably the treatment is for a conditionassociated with the deposition of β-amyloid. Preferably the condition isa neurological disease having associated β-amyloid deposition such asAlzheimer's disease.

[0239] The present invention further provides the use of a compound ofthe present invention or a pharmaceutically acceptable salt thereof inthe manufacture of a medicament for treating or preventing Alzheimer'sdisease.

[0240] Also disclosed is a method of treatment of a subject sufferingfrom or prone to Alzheimer's disease which comprises administering tothat subject an effective amount of a compound according to the presentinvention or a pharmaceutically acceptable salt thereof.

[0241] The liquid forms in which the novel compositions of the presentinvention may be incorporated for administration orally or by injectioninclude aqueous solutions, suitably flavoured syrups, aqueous or oilsuspensions, and flavoured emulsions with edible oils such as cottonseedoil, sesame oil, coconut oil or peanut oil, as well as elixirs andsimilar pharmaceutical vehicles. Suitable dispersing or suspendingagents for aqueous suspensions include synthetic and natural gums suchas tragacanth, acacia, alginate, dextran, sodium carboxymethylcellulose,methylcellulose, polyvinyl-pyrrolidone or gelatin.

[0242] For treating or preventing Alzheimer's Disease, a suitable dosagelevel is about 0.01 to 250 mg/kg per day, preferably about 0.01 to 100mg/kg per day, and especially about 0.01 to 5 mg/kg of body weight perday. The compounds may be administered on a regimen of 1 to 4 times perday. In some cases, however, dosage outside these limits may be used.

[0243] There is also provided a process for producing a compound offormula I or a pharmaceutically acceptable salt thereof which comprisesreacting a compound of formula II with a compound of formula III:

[0244] wherein R¹, R², R³, R⁴, R⁵, A, X and n are as defined above and Pis hydrogen or a protecting group such as a trialkylsilane group, forexample t-butyl dimethylsilyl, followed, if necessary, by deprotectionof the resulting compound to produce a compound of formula I. Thereaction is generally carried out in the presence of coupling agentssuch as 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and1-hydroxybenzotriazole in a solvent such as DMF, generally at about roomtemperature for six to twelve hours. Any necessary deprotection isachieved by conventional means.

[0245] The compound of formula II is produced by reacting a compound offormula IV:

[0246] wherein R¹, R², R³ and X are as defined above in a solvent suchas dioxane, with a base such as lithium hydroxide in a polar solventsuch as water generally at room temperature for above five hours. Ifdesired the resulting compound of formula II in which P is hydrogen isprotected by conventional means.

[0247] The compound of formula IV is produced by reacting a compound offormula V with a compound of formula VI or a compound of formula VII:

[0248] wherein R¹, R² and X are as defined above, R³′ is the acylderivative of a group R³ as defined above and R³″ is a group R³ bound toan oxo group at the portion of R³ which connects to the compound offormula V. The reaction is generally carried out in the presence of abase such as lithium diisopropylamide in a solvent such as THF generallycooled to −78° C. for about thirty minutes. The reaction mixture issubsequently dehydrated without purification and then hydrogenated with,for example, hydrogen over 5% Pd/C catalyst at about 50 psi for about 2h.

[0249] The compound of formula V in which R¹ is tertiary butyl and R² isbenzyl can be prepared as described by J. Litera et al., Collect. Czech.Chem. Commun. 1998, 63, 231ff. Compounds of formula V in which R¹ isother than tertiary butyl and R² is other than benzyl can be made byanalogous methods.

[0250] Compounds of formulae III and VI are commercially available orknown in the prior art or can be made from commercially available orknown compounds by standard methods.

[0251] Alternatively the compounds of the present invention can be madeby the following typical experimental procedure or by methods analogousthereto:

[0252] in which R¹, R², R³, R⁴, R⁵ and n are as defined above and A ishydrogen.

[0253] A. 50 mg (0.030 mmol) of FMOC-Sieber amide resin is placed in aQuest 210 solid phase reactor and treated with Piperidine/DMF (0.5 mL;1:1 mixture) with mixing for 30 minutes. The reactor is drained andwashed with DMA (10×1 mL). 1 mL of a 0.1 M solution of FMOC-amino acid 1in DMA is added followed by 0.2 mL of a DMA mixed solution of HOBT andHunig's base (0.5 M in both) and 0.5 mL of a 0.2 M solution of PyBOP inDMA. The reactor is mixed for 60 minutes, drained, and washed with DMA(10×1 mL). The reactor is treated with Piperidine/DMF (0.5 mL; 1:1mixture) and mixed for 30 minutes. The reactor is drained and washedwith DMA (10×1 ML). 1 mT. of a 0.1 M solution of FMOC-amino acid 2 inDMA is added followed by 0.2 mL of a DMA mixed solution of HOBT andHunig's base (0.5 M in both) and 0.5 mL of a 0.2 M solution of PyBOP inDMA. The reactor is mixed for 60 minutes, drained, and washed with DMA(10×1 mL). The reactor is treated with Piperidine/DMF (0.5 mL; 1:1mixture) and mixed for 30 minutes. The reactor is drained and washedwith DMA (10×1 mL).

[0254] B. 21 mg (0.04 mmol) of the TBS-protected isostere and 5 mg HOBTin 0.5 mL NMP is added to the reactor, followed by Hunig's base (50 μL)and 0.5 M PyBOP in NMP (0.5 mL). The reactor is mixed for 16 h,filtered, and washed with DMA (5×1 mL), MeOH (2×1 mL) and DCE (10×1 mL).

[0255] C. The reactor is treated with 0.5 mL of a 1% solution of TFA inDCM and stood for 10 minutes. The reactor is drained into a test tubecontaining 2 M NH₃ in MeOH (1 mL) and the cleavage repeated a further 5times (identical conditions). The product is concentrated (SpeedVac),dissolved in 1 mL DCM and washed with water (1 mL) using a phaseseparation CombiTube. The DCM layer is concentrated (SpeedVac) to giveessentially pure TBS-protected product.

[0256] D. The product is dissolved in 1 M TBAF in THF (0.5 mL), stoodfor 7 h, water (2 mL) is added and the product is extracted out with DCM(3×1 mL). The product is purified by flash chromatography (5%MeOH/DCM).

[0257] All products are analyzed by analytical LC-MS utilizing diodearray detection (210-250 nm) and APcI detection (150-850 amu) using afull 5% →95% MeCN gradient with 0.1% aqueous TFA. A strong M+Na⁺ peak isoberved in the mass spectrum.

[0258] It will be understood that any compound of formula I initiallyobtained from the above process may, where appropriate, subsequently beelaborated into a further compound of formula I by techniques known fromthe art.

[0259] It will also be appreciated that where more than one isomer canbe obtained from a reaction then the resulting mixture of isomers can beseparated by conventional means.

[0260] Where the above-described process for the preparation of thecompounds according to the invention gives rise to mixtures ofstereoisomers, these isomers may be separated by conventional techniquessuch as preparative chromatography. The novel compounds may be preparedin racemic form, or individual enantiomers may be prepared either byenantiospecific synthesis or by resolution.

[0261] During any of the above synthetic sequences it may be necessaryand/or desirable to protect sensitive or reactive groups on any of themolecules concerned. This may be achieved by means of conventionalprotecting groups, such as those described in Protective Groups inOrganic Chemistry, ed. J. F. W. McOmie, Plenum Press, 1973; and T. W.Greene & P. G. M. Wuts, Protective Groups in Organic Synthesis, JohnWiley & Sons, 1991. The protecting groups may be removed at a convenientsubsequent stage using methods known from the art.

[0262] A typical assay which can be used to determine the level ofactivity of compounds of the present invention is as follows:

[0263] (1) Mouse neuroblastoma neuro 2a cells expressing human app695are cultured at 50-70% confluency in the presence of sterile 10 mMsodium butyrate.

[0264] (2) Cells are placed in 96-well plates at 30,000/well/100 μL inminimal essential medium (MEM) (phenol red-free) +10% foetal bovineserum (FBS), 50 mM HEPES buffer (pH7.3), 1% glutamine, 0.2 mg/mL G418antibiotic, 10 mM sodium butyrate.

[0265] (3) Make dilutions of the compound plate. Dilute stock solutionto 5.5% DMSO/110 μM compound. Mfix compounds vigorously and store at 4°C. until use.

[0266] (4) Add 10 μL compound/well. Mix plate briefly, and leave for 18h in 37° C. incubator.

[0267] (5) Remove 90 μL of culture supernatant and dilute 1:1 withice-cold 25 mM HEPES (pH.3), 0.1% BSA, 1.0 mM EDTA (+broad spectrumprotease inhibitor cocktail; pre-aliquotted into a 96-well plate). Mixand keep on ice or freeze at −80° C.

[0268] (6) Add back 100 μL of warm MEM +10% FBS, 50 mM HEPES (pH7.3), 1%glutamine, 0.2 mg/mL G418, 10 mM sodium butyrate to each well, andreturn plate to 37° C. incubator.

[0269] (7) Prepare reagents necessary to determine amyloid peptidelevels, for example by ELISA assay

[0270] (8) To determine if compounds are cytotoxic cell viabilityfollowing compound administration is assessed by the use of redox dyereduction. A typical example is a combination of redox dye MTS (Promega)and the electron coupling reagent PES. This mixture is made up accordingto the manufacturer's instructions and left at room temperature.

[0271] (9) Quantitate amyloid beta 40 and 42 peptides using anappropriate volume of diluted culture medium by standard ELISAtechniques.

[0272] (10) Add 15 μL/well MTS/PES solution to the cells; mix and leaveat 37° C.

[0273] (11) Read plate when the absorbance values are approximately 1.0(mix briefly before reading to disperse the reduced formazan product).

[0274] The Examples of the present invention all had an ED₅₀ of lessthan 500 nM, preferably less than 200 nM and most preferably less than100 nM in the above assay.

[0275] The following examples illustrate the present invention.

EXAMPLE 1{1S-Benzyl-4R-[1-(1S-carbamoyl-2-(R)-hydroxypropylcarbamoyl)-(S)-ethylcarbamoyl]-2R-hydroxy-5-phenylpentyl}-carbamicacid, tert-butyl ester Step 1:[1S-(4M-Benzyl-5-oxo-tetrahydrofuran-2R-yl)-2-phenylethyl]-carbamicacid, tert-butyl ester

[0276] A solution of[1S-(5-oxo-tetrahydrofuran-2R-yl)-2-phenylethyl]-carbamic acid,tert-butyl ester (prepared as described in J. Litera et al., Collect.Czech. Chem. Commun. 1998, 63, 231) (3.0 g, 0.99 mmol) in THF (10 ml)was added to a solution of lithium diisopropylamide [made fromn-butyllithium (8.64 ml of a 2.5 M solution in hexane) anddiisopropylamine (3.06 ml)] in THF (10 ml) at −78° C. The reactionmixture was stirred for 40 minutes at −78° C., then treated withbenzaldehyde. After 30 minutes, the reaction mixture was quenched by theaddition of aqueous NH₄Cl (5 ml) and water. The resulting mixture wasextracted with ethyl acetate and the combined extracts were washed withaqueous citric acid, aqueous NaHRO₃ solution and brine. The combinedextracts were dried (MgSO₄), filtered and evaporated in vacuo to give athick oil. This crude reaction product was treated with acetic anhydride(5 ml), triethylamine (5 ml) and heated at 120° C. for 1 h. The reactionmixture was cooled to room temperature, diluted with ether and washedwith aqueous citric acid, aqueous NaHCO₃ solution and brine. Theethereal extracts were dried (MgSO₄) and evaporated in vacuo to give thereaction product as a crude solid which was used without furtherpurification. This crude reaction product was dissolved in ethyl acetate(25 ml) and methanol (5 ml), treated with 5% Pd/C catalyst andhydrogenated at 50 psi for 2 h. The reaction mixture was filtered andevaporated in vacuo to give the title compound, which was eitherpurified by flash column chromatography, or by trituration with ether,(yield 3.9 g, 78%). ¹H NMR (250 MHz, CDCl₃) 7.38-7.15 (10 H, m);4.38-4.11 (2 H, m), 3.90 (1 H, brs); 3.27 (1 H, dd, J=13.7, 4.0);2.95-2.67 (4 H, m), 2.28-2.17 (1 H, m); 1.86-1.70 (1 H, m); 1.34 (9 H,s).

Step 2:2R-Benzyl-5S-tert-butoxycarbonylamino-4R-(tert-butyldimethylsilanyloxy)-6-phenyl-hexanoicacid

[0277] The compound obtained in Step 1 (2.0 g, 5.1 mmol) was dissolvedin 1,2-dimethoxyethane (36 mL) and treated with a solution of sodiumhydroxide in water (1.0 M, 36 mL, 1.1 equiv.) and stirred at roomtemperature for 0.5 h. The reaction mixture was carefully acidified topH 4 with citric acid, then extracted with ethyl acetate. The ethylacetate extracts were washed with brine, dried (MgSO₄), filtered andevaporated in vacuo. The crude hydroxyacid was dissolved in DMF (20 mL)and treated with tert-butyldimethylsilyl chloride (7.8 g, 5 equiv.) andimidazole (4.2 g, 10 equiv.) and stirred overnight. The reaction mixturewas treated with methanol and stirred for 2 h, then evaporated in vacuo.The reaction mixture was partitioned between aqueous citric acid andethyl acetate. The organic layer was washed with brine, dried (MgSO₄),filtered and evaporated in vacuo. Purification by flash columnchromatography gave the title compound (2.55 g, 95%) 1H NMR (400 MHz,d₆-DMSO) 12.08 (1 H, s); 7.25-7.04 (10 H, m); 6.45 (1 H, d, J =8.9);3.74-3.53 (2 H, m); 2.76-2.50 (5 H, m); 1.8-1.5 (2 H, m); 1.22 (9 H, s);0.80 (9 H, s); 0.07 (3 H, s); 0.05 (3H, s).

Step 3:{1S-Benzyl-4R-[1-(1S-carbamoyl-2-(R)-hydroxypropylcarbamoyl)-(S)-ethylcarbamoyl]-2R-hydroxy-5-phenylpentyl}-carbamicacid. tert-butyl ester

[0278] The compound obtained in Step 2 (50 mg), H₂N-L-ala-L-thr-CONH₂(20 mg), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (22mg) and 1-hydroxybenzotriazole (15 mg) in DMF was stirred at roomtemperature overnight. The reaction mixture was diluted with ethylacetate, and the organic phase was washed with aqueous citric acid,aqueous NaHCO₃, brine, dried (MgSO₄), filtered and evaporated in vacuo.Purification by flash column chromatography gave the product (40 mg,60%). This material was dissolved in a solution of tetrabutylammoniumfluoride in THF (1.0 M, 2 ml) and stirred at room temperature overnight.The reaction mixture was diluted with citric acid and ether and theresulting precipitate was collected by filtration, washed and dried invacuo to give the title compound. (19 mg, 57%) 1H NMR (360 MHz, d₆-DMSO)8.02 (1 H, d, J=6.8); 7.44 (1 H, d, J =7.9); 7.26-7.08 (12 H, m); 6.51(1 H, d, J=8.9); 4.89 (1 H, brs); 4.67 (1 H, brs); 4.27-4.23 (2 H, brm);4.04 (2 H, m); 3.4 (2 H, m); 2.9-2.4 (4 H, m); 1.60-1.56 (2 H, m);1.24-0.99 (15 H, m). In the same way as for Step 3 using the appropriateamine the following compounds were also made:

EXAMPLE 2{1S-Benzyl-4R-[1-(1S-carbamoyl-2-(S)-methylbutylcarbamoyl)-1S-2-methylpropylcarbamoyl]-2R-hydroxy-5-phenylpentyl}-carbamicacid, tert-butyl ester

[0279]¹H NMR (360 MHz, d₆-DMSO) 7.53 (1 H, d, J =8.7); 7.42 (1 H, d, J=8.7); 7.23-7.10 (12 H, m); 6.2 (1 H, vbrs); 4.48 (1H, brs); 4.19-4.09(2 H, m); 3.56-3.52 (2 H, m); 2.91-2.54 (5 H, m); 2.00-1.95 (1 H, m);1.74-1.61 (3 H, m); 1.46-0.80 (23 H, m).

EXAMPLE 3{1S-Benzyl-4-[1-(5-cyclohexyl-2-oxo-2,3-dihydro-1H-benzo[e][1,4]diazepin-3(R,S)-ylcarbamoyl)-(S)-ethylcarbamoyl]-2R-hydroxybutyl}-carbamicacid, tert-butyl ester

[0280]¹H NMR (400 MHz, d₆-DMSO) 10.63 (0.5 H, s); 10.58 (0.5 H, s); 8.78(0.5 H, d, J=8.2); 8.68 (0.5 H, d, J=8.2); 7.96 (1 H, m); 7.73 (1 H, m);7.55-7.51 (1 H, m); 7.28-7.12 (7 H, m); 6.53-6.51 (1 H, m); 5.03-5.00 (1H, m); 4.77-4.75 (1 H, m); 4.50-4.46 (1 H, m); 3.50-3.40 (1H, m);3.00-2.85 (2 H, m); 2.40-0.80 (28 H, m).

EXAMPLE 4{1S-Benzyl-4R-[1-(5-cyclohexyl-2-oxo-2,3-dihydro-1H-benzo[e][1,4]diazepin-3(R,S)-ylcarbamoyl)-(S)-ethylcarbamoyl]-2R-hydroxy-5-phenylpentyl}-carbamicacid, tert-butyl ester

[0281]¹H NMR (400 MHz, d⁶-DMSO) 10.65 (0.5 H, s); 10.60 (0.5 H, s); 8.62(0.5 H, d, J=8.2); 8.53 (0.5 H, d, J=7.8); 7.92-7.88 (1 H, m); 7.76-7.74(1 H, m); 7.54-7.51 (1 H, m); 7.29-7.09 (12 H, m); 6.52-6.48 (1 H, m);5.00-4.98 (1 H, m); 4.65-4.60 (1 H, m); 4.50-4.40 (1 H, m); 3.51-3.38 (2H, ma); 3.0-2.4 (5 H, m); 2.0-1.1 (25 H, m).

EXAMPLE 5{1S-Benzyl-4R-[1-(1S-carbamoyl-2-phenylethylcarbamoyl)-1S-3-methylbutylcarbamoyl]-2R-hydroxy-5-phenylpentyl}-carbamicacid, benzyl ester

[0282] 7.89 (1 H, d, J=7.2); 7.65 (1 H, d, J=7.2); 7.35-7.02 (23 H, m);4.98-4.78 (3 H, m); 4.44-4.37 (1 H, m); 4.22-4.10 (1 H, m); 3.60-3.52 (1H, m); 3.52-3.42 (1 H, m); 3.02-2.98 (1 H, m); 2.90-2.40 (6 H, m);1.70-1.20 (5 H, m); 0.81 (3 H, d, J=6.5); 0.75 (3 H, d, J=6.5).

EXAMPLE 6{1S-Benzyl-4R-[1-(1S-carbamoyl-2-phenylethylcarbamoyl)-1S-3-methylbutylcarbamoyl]-2-oxo-5-phenylpentyl}-carbamicacid tert-butyl ester

[0283]{1S-benzyl-4R-[1-(1S-carbamoyl-2-phenylethylcarbamoyl)-1S-3-methylbutylcarbamoyl]-2S-hydroxy-5-phenylpentyl}-carbamicacid tert-butyl ester (S. J. deSolms et al, J. Med. Chem., 1991, 34,2852) (68.9 mg, 0.10 mmol) was dissolved in glacial acetic acid (3 mL)and treated with pyridinium dichromate (92 mg, 0.25 mmol) and stirredfor 3 h at room temperature. The reaction mixture was carefullyneutralized with NaHCO3 solution and extracted with ethyl acetate. Thecombined organic extracts were washed with NaHCO3 solution, dried(MgSO4), filtered and evaporated in vacuo. Trituration with ethylacetate gave the title compound, (49.6 mg, 72%).

[0284] The following three compounds were made by methods describedherein using FMOC-Sieber amide resin:

EXAMPLE 7{1S-Benzyl-4R-[1-(1S-carbamoyl-2-phenylethylcarbamoyl)-1S-3-methyl-butylcarbamoyl]-2R-hydroxy-5-phenylpentyl}carbamicacid tert-butyl ester

[0285]¹H NMR (d₆-DMSO, 360 MHz) δ 7.88 (1H, d, J=8 Hz), 7.63 (1 H, d,J=8 Hz), 7.28-7.06 (17 H, m), 6.47 (1 H, d, J=9.3 Hz), 4.71 (1 H, d,J=5.3 Hz), 4.40 (1 H, m), 4.16 (1 H, m), 3.50-2.30 (7 H, m), 1.70-1.30(5 H, m), 1.24 (9 H, s), 1.10 (1 H, s), 0.82 (3 H, d, J=6.6 Hz), 0.76 (3H, d, J=6.6 Hz). LC-MS (APcI) 673 (M+H⁺), 695 (M+Na⁺).

EXAMPLE 8{1S-Benzyl-4R-[1-(1S-carbamoyl-2-phenylethylcarbamoyl)-S-ethylcarbamoyl]-2R-hydroxy-5-phenylpentyl}carbamicacid tert-butyl ester

[0286]¹H NMR (d₆-DMSO, 360 MHz) δ 7.90 (1H, d, J=8 Hz), 7.66 (1 H, d,J=8 Hz), 7.28-7.06 (17 H, m), 6.49 (1 H, d, J=9.3 Hz), 4.82 (1 H, d,J=5.3 Hz), 4.43 (1 H, m), 4.18 (1 H, m), 3.50-2.30 (7 H, m), 1.70-0.90(15 H, m). LC-MS (APcI) 631 (M+H⁺), 653 (M+Na⁺).

EXAMPLE 9(1S-Benzyl-4R-{1S-[(-carbamoylphenylmethyl)carbamoyl]-S-ethylcarbamoyl}-2R-hydroxy-5-phenylpentyl)carbamicacid tert-butyl ester

[0287]¹H NMR (d6-DMSO, 360 MHz) δ 8.11 (1H, d, J=8 Hz), 7.74 (1 H, d,J=8 Hz), 7.28-7.06 (17 H, m), 6.45 (1 H, d, J=9.3 Hz), 4.75 (1 H, d,J=5.3 Hz), 4.41 (1 H, m), 4.17 (1 H, m), 3.50-2.30 (5 H, m), 1.70-0.90(15 H, m). LC-MS (APcI) 617 (M+H⁺), 639 (M+Na⁺).

[0288] For the avoidance of doubt the structures of the specificExamples of the present invention are as follows. In the case ofambiguity in the names given herein the structures below are to be takenas correct. Structure Example Number

Example 1

Example 2

Example 3

Example 4

Example 5

Example 6

Example 7

Example 8

Example 9

1. A compound of formula I or a pharmaceutically acceptable saltthereof:

wherein: R¹ is (1) C₁₋₁₀alkyl, C₂₋₁₀alkenyl or C₂₋₁₀alkynyl optionallysubstituted with one to three substituents independently chosen from:(i) hydroxy; (ii) carboxy; (iii) halogen; (iv) C₁₋₄alkoxy; (v)C₁₋₄alkoxycarbonyl; (vi) —NR⁶R⁷ wherein R⁶ and R⁷ are independentlychosen from hydrogen, C₁₋₅alkyl and C₁₋₅alkoxyC₁₋₅alkyl; (vii) —CONR⁶R⁷or OCONR⁶R⁷ wherein R⁶ and R⁷ are independently as defined above; (viii)—N(R⁸)QR⁹ wherein: Q is C(O), C(S), SO₂ or C(NH₂); R⁸ is hydrogen orC₁₋₄alkyl; and R⁹ is hydrogen, C₁₋₄alkyl, C₁₋₄alkoxy, amino,C₁₋₄alkylamino di(C₁₋₄alkyl)amino wherein each alkyl group isindependently chosen; (ix) C₃₋₇cycloalkyl; (x) phenyl or naphthyl; afive-membered heterocyclic ring containing 1, 2, 3 or 4 heteroatomsindependently chosen from O, N and S, at most one of the heteroatomsbeing O or S; a six-membered heterocyclic ring containing 1, 2 or 3nitrogen atoms; each of which is optionally substituted by one to threegroups independently chosen from: (a) halogen, cyano and nitro, (b)hydroxy, (c) C₁₋₄alkyl, C₂₋₄alkenyl and C₂₋₄alkynyl, (d) C₁₋₄alkoxy, (e)NR⁶R⁷ wherein R⁶ and R⁷ are independently as defined above, (f) CO₂R⁸wherein R⁸ is independently as defined above, (g) CONR⁶R⁷ or OCONR⁶R⁷wherein R⁶ and R⁷ are independently as defined above, (h) SO₂NR⁶R⁷wherein R⁶ and R⁷ are independently as defined above, (i) CH₂NR⁶R⁷wherein R⁶ and R⁷ are independently as defined above, (j) N(R⁸)COR^(8′)wherein R⁸ is independently as defined above and R^(8′) is independentlyas defined for R⁸, and (k) NR⁸SO₂R^(8′) wherein R⁸ and R^(8′) areindependently as defined above; or (2) phenyl or naphthyl; afive-membered heterocyclic ring containing 1, 2, 3 or 4 heteroatomsindependently chosen from O, N and S, at most one of the heteroatomsbeing O or S; a six-membered heterocyclic ring containing 1, 2 or 3nitrogen atoms; each of which is optionally substituted by one to threegroups independently chosen from:  (a) halogen, cyano and nitro,  (b)hydroxy,  (c) C₁₋₄alkyl, C₂₋₄alkenyl and C₂₋₄alkynyl,  (d) C₁₋₄alkoxy, (e) NR⁶R⁷ wherein R⁶ and R⁷ are independently as defined above,  (f)CO₂R⁸ wherein R⁸ is independently as defined above,  (g) CONR⁶R⁷ orOCONR⁶R⁷ wherein R⁶ and R⁷ are independently as defined above,  (h)SO₂NR⁶R⁷ wherein R⁶ and R⁷ are independently as defined above,  (i)CH₂NR⁶R⁷ wherein R⁶ and R⁷ are independently as defined above,  (j)N(R⁸)COR⁸′ wherein R⁸ and R^(8′) are independently as defined above, and (k) NR⁸SO₂R^(8′) wherein R⁸ and R^(8′) are independently as definedabove; R² and R³ are independently chosen from C₁₋₁₀alkyl, C₁₋₁₀alkoxy,C₂₋₁₀alkenyl, C₂₋₁₀alkenyloxy, C₂₋₁₀alkynyl or C₂₋₁₀alkynyloxy; phenyl;naphthyl; a five-membered heteroaromatic ring containing 1, 2, 3 or 4heteroatoms independently chosen from O, N and S, at most one of theheteroatoms being O or S; a six-membered heteroaromatic ring containing1, 2 or 3 nitrogen atoms; and a group (CH₂)_(p)Q¹ wherein Q¹ is phenyl,naphthyl, a five-membered heteroaromatic ring containing 1, 2, 3 or 4heteroatoms independently chosen from O, N and S, at most one of theheteroatoms being O or S, and a six-membered heteroaromatic ringcontaining 1, 2 or 3 nitrogen atoms; and wherein each of R² and R³ isindependently optionally substituted by one to three groupsindependently chosen from: (a) halogen, cyano and nitro, (b) hydroxy,(c) C₁₋₃alkyl, C₂₋₃alkenyl and C₂₋₃alkynyl, (d) C₁₋₃alkoxy, (e) NR⁶R⁷wherein R⁶ and R⁷ are independently as defined above, (f) CO₂R⁸ whereinR⁸ is independently as defined above, (g) CONR⁶R⁷ or OCONR⁶R⁷ wherein R⁶and R⁷ are independently as defined above, (h) SO₂NR⁶R⁷ wherein R⁶ andR⁷ are independently as defined above, (i) CH₂NR⁶R⁷ wherein R⁶ and R⁷are independently as defined above, (j) N(R⁸)COR^(8′) wherein R⁸ andR^(8′) are independently as defined above, and (k) NR⁸SO₂R^(8′) whereinR⁸ and R^(8′) are independently as defined above; alternatively R³ maybe hydrogen; R⁴ and R⁵ are independently chosen from hydrogen,C₁₋₆alkyl, optionally substituted by halogen, hydroxy, thiol, amino,C₁₋₄alkoxy, C₁₋₄alkylthio, carboxy, C₁₋₄alkoxycarbonyl and (CH₂)_(q)Q²wherein Q² is a five-membered unsaturated heterocycle containing 1, 2, 3or 4 heteroatom optionally chosen from O, N, and S providing that notmore than one heteroatom is O or S, a six-membered unsaturatedheterocycle containing 1, 2 or 3 N atoms and phenyl and naphthyl, or afused ring which is indolyl, each of the foregoing rings beingoptionally substituted with one to three groups independently chosenfrom hydroxy, C₁₋₄alkyl, C₁₋₄alkoxy, thiol, C₁₋₄alkylthio, halogen,amino, carboxy, amido, CO₂H and —NHC(NH₂)₂ and wherein each of theforegoing rings is optionally fused to a benzene ring; and A is: (1)hydrogen (2) C₁₋₁₀alkyl, C₂₋₁₀alkenyl or C₂₋₁₀alkynyl optionallysubstituted with one to three substituents independently chosen from:(i) hydroxy; (ii) carboxy; (iii) halogen; (iv) C₁₋₄alkoxy; (v)C₁₋₄alkoxycarbonyl; (vi) —NR⁶R⁷ wherein R⁶ and R⁷ are independentlychosen from hydrogen, C₁₋₅alkyl and C₁₋₅alkoxyC₁₋₅alkyl; (vii) —CONR⁶R⁷or OCONR⁶R⁷ wherein R⁶ and R⁷ are independently as defined above; (viii)—N(R⁸)QR⁹ wherein: Q is C(O), C(S), SO₂ or C(NH₂); R⁸ is hydrogen orC₁₋₄alkyl; and R⁹ is hydrogen, C₁₋₄alkyl, C₁₋₄alkoxy, amino,C₁₋₄alkylamino di(C₁₋₄alkyl)amino wherein each alkyl group isindependently chosen; (ix) C₃₋₇cycloalkyl; (x) phenyl or naphthyl; afive-membered heterocyclic ring containing 1, 2, 3 or 4 heteroatomsindependently chosen from O, N and S, at most one of the heteroatomsbeing O or S; a six-membered heterocyclic ring containing 1, 2 or 3nitrogen atoms; each of which is optionally substituted by one to threegroups independently chosen from: (a) halogen, cyano and nitro, (b)hydroxy, (c) C₁₋₄alkyl, C₂₋₄alkenyl and C₂₋₄alkynyl, (d) C₁₋₄alkoxy, (e)NR⁶R⁷ wherein R⁶ and R⁷ are independently as defined above, (f) CO₂R⁸wherein R⁸ is independently as defined above, (g) CONR⁶R⁷ or OCONR⁶R⁷wherein R⁶ and R⁷ are independently as defined above, (h) SO₂NR⁶R⁷wherein R⁶ and R⁷ are independently as defined above, (i) CH₂NR⁶R⁷wherein R⁶ and R⁷ are independently as defined above, (j) N(R⁸)COR^(8′)wherein R⁸ is independently as defined above and R^(8′) is independentlyas defined for R⁸, and (k) NR⁸SO₂R^(8′) wherein R⁸ and R^(8′) areindependently as defined above; (3) a seven-membered heterocycle havingan otherwise unsubstituted carbon atom at the point of attachment to therest of the compound of formula I, having at a first atom alpha to thepoint of attachment a carbon atom which is unsubstituted or substitutedby an oxygen or sulphur atom, having at a first atom beta to the pointof attachment, which atom is alpha to the foregoing first atom alpha, acarbon atom or a nitrogen atom, having at a second atom alpha to thepoint of attachment a carbon atom, which is optionally substituted byoxygen, or a nitrogen atom, having at a second atom beta to the point ofattachment, which atom is alpha to the foregoing second atom alpha, acarbon atom or a nitrogen atom, and having at the two remaining atomscarbon atoms; a double bond may be present between the second atom alphaand the second atom beta; the seven-membered heterocycle may be fused toone or two aromatic rings via any adjacent pair of atoms other than thepoint of attachment and the first atom alpha alone or in combination;the aromatic ring may be benzene or a five-membered heterocyclecontaining 1, 2, 3 or 4 heteroatoms chosen from O, N and S